The present invention utilizes functions claimed in our previous U.S. Pat. No. 5,031,412, granted Jul. 16, 1991.
1. Field of Invention
This invention relates to evaporative coolers, specifically to a control system for evaporative coolers. Control devices are installed to allow a person to control the evaporative cooler away from the wall-mounted control switch.
2. Discussion of Prior-art
Evaporative coolers, also known as swamp coolers, are best suited to dry, desert climates, such as that found in the southwestern United States. Evaporative coolers generally comprise a generally cubic structure three to four feet (1 to 1.3 meters) in length, height, and width that is commonly mounted on the exterior of the roof of the building to be cooled. Three or four surfaces of the evaporative cooler comprise removable frames that contain pads made of shredded aspen wood or paper. The bottom of the evaporative cooler contains water to a depth that is controlled by a float to be about four inches (10 centimeters). The water is circulated by a water pump through distribution tubes to the tops of the pads to keep them wet. A blower fan centrally located within the evaporative cooler pulls dry outside air through the wet pads and into a duct distribution system located within the building. The power cords of the motor and pump protrude through the evaporative cooler housing and are plugged into a roof-mounted electrical disconnect box, commonly known as a Midwest box. Prevalently used to control the evaporative cooler, is a manually operated control switch. This switch is wall-mounted and allows the user to select a combination of water pump and blower fan settings. An exemplary prior-art evaporative cooler is described in U.S. Pat. No. 4,379,712 to Speer (1983).
Evaporative coolers differ significantly from refrigerated air conditioning units in a number of ways.
An air conditioner recirculates and tempers the air inside the building, while an evaporative cooler permits fresh outside air, cooled through wet pads, to enter the building and exit through open windows.
Air conditioners are cycled on and off during the course of the day and night by thermostats that control them, whereas prior-art evaporative coolers run continuously.
One of the problems associated with prior-art evaporative coolers is the user""s dilemma at bedtime. If the cooler is turned off before going to sleep, the inside air temperature of the building will most likely rise due to the heat stored in the building""s walls and cause the occupants to become uncomfortable. Conversely, if the cooler is left on when going to sleep, the occupants will probably become too cold during the night, and have to get out of bed, go to the wall-mounted control switch, and shut off the cooler.
Another problem associated with prior-art evaporative coolers, is their high water usage, on the order of 15-20 gallons (55-75 liters) per hour. Shutting the evaporative cooler off when it is not needed or at times when the building is not occupied can result in significant savings of water and electrical energy. As an example, it has been estimated that approximately 10 billion gallons (40 gigaliters) per year are used in Tucson, Arizona in connection with the operation of residential evaporative coolers. This represents a major percentage of Arizona""s water usage.
The prevalent system that controls evaporative coolers is a simple, six-position rotary control switch. This switch is wall-mounted and allows the user to select a combination of water pump and blower fan settings. This switch is manually operated and does not address nor solve the problem of high water usage of evaporative coolers. In the desert, water is precious, so the ability to control the operation of evaporative coolers would result in a significant savings of this precious natural resource.
Shutting off an evaporative cooler can cause a building to become hot and take a few hours to cool down after turning the cooler back on. Presently, it is common for occupants to run their evaporative cooler continuously to prevent having a hot house. Many of these people would gladly or even prefer to shut their cooler off during unneeded periods, if an appropriate controller was available to them. The controller would turn the cooler on and cool the building down before the occupants returned. Shutting evaporative coolers off during unneeded periods would save a significant amount of water and electrical energy.
There have been a number a attempts in the prior-art to solve the problem of controlling evaporative coolers through the use of thermostats. Exemplary prior-art is U.S. Pat. Nos. 4,232,531 to Mangum (1980), U.S. Pat. No. 4,560,972 to Britt (1985), U.S. Pat. No. 4,580,403 to Hummel (1986), U.S. Pat. No. 4,673,028 to Meland (1987), and U.S. Pat. No. 4,775,100 to Gouldey (1988). However, control of evaporative coolers is not effectively accomplished using temperature-responsive devices, for a number of reasons.
In order for an evaporative cooler to work properly, some windows in the building must be open in order to relieve air pressure created by the cooler. After the thermostat turns off the cooler, the open windows will permit hot outside air to enter the building thereby causing rapid cycling of the evaporative cooler and defeating the purpose of the thermostat.
Evaporative coolers do not recirculate and thereby mix the inside air. As a result, it is very difficult to position a thermostat for controlling an evaporative cooler in a location that will provide good temperature sensing. The above Pat. No. 4,560,972 to Britt describes a line voltage thermostat for controlling evaporative coolers. This device is intended to replace the conventional control switch. However, these control switches are generally in hallways or closets, which are unacceptable locations for sensing the inside air temperature.
Thermostat control results in cooling a building, whether or not it is occupied, thereby causing a waste of water and energy.
The line voltage thermostats described in the above Pat. No. 4,560,972 to Britt and U.S. Pat. No. 4,775,100 to Gouldey have a wide temperature range of plus or minus 20xc2x0 F. (11xc2x0 C.) in order to prevent rapid cycling of the evaporative cooler due to open windows as described earlier. The use of these thermostats results in unpredictable cycling, and generally results in the evaporative cooler being turned on and off once every day.
A major problem in retrofitting an existing evaporative cooler control system is that the conventional systems have only four wires to the wall-mounted control switch and four wires to the roof-mounted electrical disconnect box. The wires to the control switch box are designated Hot, High motor, Low motor, and Pump. There is no neutral wire to the wall box, which would be needed to power a controller if it were to be mounted in place of the manual control switch. The wires to the electrical disconnect box are designated Neutral, High motor, Low motor, and Pump. There is no hot wire to the electrical disconnect box, which would be needed to power a controller if it were to be mounted in the electrical disconnect box. The above Pat. No. 4,580,403 to Hummel, U.S. Pat. No. 4,673,028 to Meland, and U.S. Pat. No. 4,932,218 to Robbins (1990) describe evaporative cooler controllers that require additional electrical wiring and constructional changes to buildings in which an evaporative cooler has been previously installed. These could require a difficult and expensive installation.
U.S. Pat. No. 4,200,862 to Campbell (1980) describes a system for controlling appliances from a master control panel that is plugged into any of the building""s electric outlets. The appliance is plugged into a slave unit that is plugged into any of the building""s electric outlets. The master control panel controls the slave unit and thereby the appliance, by transmitting electric signals through the building""s power wires. This is commonly known today as power line carrier (PLC) technology.
The above Pat. No. 4,200,862 to Campbell was assigned to Pico Electronics Limited, whose parent company, X-10 Limited was very successful with this product. Today, X-10 sells an extensive PLC product line under the trademarks of Powerhouse and Activehome. There are other companies as well who sell PCL product lines, both X-10 compatible or using other technology standards.
Pico Electronics has several other PLC patents, specifically U.S. Pat. No. 4,189,713 to Duffy (1980), U.S. Pat. No. 4,377,754 to Thompson (1983), U.S. Pat. No. 4,628,440 to Thompson (1986), U.S. Pat. No. 4,638,299 to Campbell (1987), and U.S. Pat. No. 5,005,187 to Thompson (1991). Many other patents have been issued which further develop or utilize PLC technology, specifically U.S. Pat. No. 4,065,763 to Whyte (1977), U.S. Pat. No. 4,205,360 to Drucker (1980), U.S. Pat. No. 4,300,126 to Gajjar (1981), U.S. Pat. No. 4,746,897 to Shuey (1988), U.S. Pat. No. 4,885,563 to Johnson (1989), U.S. Pat. No. 5,066,939 to Mansfield (1991), and U.S. Pat. No. 5,475,360 to Guidette (1995). None of these companies have developed a system to control evaporative coolers.
It is accordingly an object of the present invention to provide a controller for evaporative coolers that:
(a) will replace the components of a conventional evaporative cooler control system,
(b) will not requiring the addition of any wires or any structural changes of the building,
(c) is easy to install,
(d) allows control of the evaporative cooler away from the location of the wall-mounted control switch,
(e) allows bedside control of the evaporative cooler,
(f) allows utilization of a variety of controllers at remote locations such as manual switches, time-clocks, thermostats, setback thermostats, telephone transponders, or computer interfaces,
(g) prevents high and low blower motor speeds from running simultaneously and
(h) allows manual control of the evaporative cooler in the event the remotely triggered modules fail and need replacement.
Further objects and advantages of the present invention will become apparent from a consideration of the drawings and ensuing description.
This invention uses remote location signal transmission to trigger control devices mounted in an existing evaporative cooler control system. The design described in this specification utilizes power line carrier (PLC) technology, such as that developed by X-10 Limited. Other signal transmission systems, such as radio frequency, radar, infrared, visible light, or ultrasonic could be utilized equally as well.
A remotely triggered (high/low) module is installed in the roof-mounted electrical disconnect box. The existing wall-mounted manually operated control switch is replaced with a new control switch. The new control switch that is described in this specification contains two manual toggle type switches and a remotely triggered (on/off) module, but other configurations could be used as well.
PLC compatible devices can then be used to control the evaporative cooler. These devices include a time-clock. The time-clock plugs into any electrical outlet of the building and would resemble a standard digital alarm clock. The time-clock sends a PLC signal to the remotely triggered modules thereby controlling the evaporative cooler.
Another PLC compatible device is a keychain remote control and transceiver system. The transceiver plugs into any electrical outlet of the building. The keychain remote control resembles those commonly used for automobile security systems and door locks. The keychain remote control sends a radio frequency (RF) signal to the transceiver, which in turn sends a PLC signal to the remotely triggered modules thereby controlling the cooler.
Other PLC compatible devices include thermostats, telephone transponders and computer interfaces. These devices, like the time-clock, and keychain remote control and transceiver systems described above, can be plugged into any standard electrical outlet of the building, control the remotely triggered modules, and thereby control the cooler.